Are the records from the Antarctic ice cores at odds with the records from the Greenland ice cores?

Asked by Chris

Hi Chris,

The rhythm of climatic variability recorded in the Antarctic ice cores is very similar to that recorded in the Greenland ice cores. A difficulty in comparison is that the Greenland ice cores tend to be a higher resolution (annual layers) than the Antarctic ice cores, which diffuse more rapidly with depth.

The ice core records have been linked using atmospheric trace gases, such as CH4; changes in the atmospheric methane content are generally equilibriated globally quickly. Changes in atmospheric methane content should therefore register contemporaneously in both polar ice sheets. There is a good match in both ice sheets between 10,000 and 52,000 years ago. age uncertainties older than this are too large for accurate matching. Ice-core records can also be linked using cosmogenic isotopes such as beryillium-10 and volcanic eruptions.

During the period 10,000 to 52,000 years ago (during an ice-age climate), the stable isotope record of the Antarctic and Greenland ice cores are anti-phased. Cooling episodes in Greenland coincide with warming episodes in Antarctica (and vice versa). The consistent anti-phase behaviour has been called the ‘bipolar seesaw’; this is a driving mechanism that transfers energy alternately between the poles. The bipolar seesaw is driven by ocean circulation changes, such as changes to the Gulf Stream.

This bipolar seesaw could operate in warmer periods, with twentieth-century climate in the Arctic and Antarctic being shown to vary in an anti-phase seesaw pattern. Warming in the Arctic has been accompanied by Antarctic cooling, and vice versa.

There are some problems with the bipolar seesaw hypothesis. For example, there are significant time lags in temperature shifts, but dating uncertainties make it difficult to ascertain which pole leads and lags. It is likely that there are other factors, in addition to ocean circulation changes, that drive anti-phased temperature patterns.

References:

Lowe and Walker, 2015. Reconstructing Quaternary Environments.

About

I am a Senior Lecturer at Newcastle Univeristy, specialising in glaciology and glacial geology. I wrote and developed the AntarcticGlaciers.org website as part of an ongoing commitment to outreach, education and research impact. Read more about me at www.antarcticglaciers.org/bethan-davies.

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